I have worked on the old ( pre unit) and I own the new ones,
get a book on any thing but Hinkley, and if you have worked on bikes you should be able to figure it out.
The generator on those models always gave me grief,
( George Lucas Prince of Darkness, and why Brits drank warm beer ) but the magneto was almost bullet proof.
650 cc is still 650cc and you can still get just about anything you want for those bikes. Mick McGuire has a list of parts suppliers at the head of this forum, British Only used to have an exploded view of a model don't remember which one.
If you have specific questions about any thing give a holler.( send PM)
Bill